Gaozu, Wade-Giles romanization Kao-tsu, personal name (xingming) Liu Bang, courtesy name (zi) Ji, posthumous name (shi) Gaohuangdi (born 256 bc, Peixian [now in Jiangsu province], China—died 195 bc, China), temple name (miaohao) of the founder and first emperor of the Han dynasty (206 bc–ad 220), under which the Chinese imperial system assumed most of the characteristics that it was to retain until it was overthrown in 1911/12. He reigned from 206 to 195 bc. His wife, the empress Gaohou (reigned 188–180 bc), became the first female ruler of China.

Born of a peasant family, Liu Bang began his career as a police officer under the Qin dynasty (221–207 bc). He turned rebel after the death (210 bc) of the Qin emperor Shihuangdi, who had been the first to unify China. The rebels were under the nominal leadership of Xiang Yu, a warlord who defeated the Qin armies and then tried to restore the pre-Qin feudal system, reinstating many of the former nobles and dividing the land among his generals. Liu Bang, by then an important rebel leader, received control of the kingdom of Han in western China (what is now Sichuan and southern Shaanxi provinces). The former allies soon turned against each other, and Liu’s peasant shrewdness led him to victory over the militarily brilliant but politically naive Xiang Yu. The civil war ended when Xiang Yu took his own life in 202 bc, upon which Gaozu became the ruler of China.

Liu Bang was a coarse man who once urinated into the formal hat of a court scholar to show his disdain for education. Nevertheless, he was a pragmatic and flexible ruler who recognized the need for educated men at court. He showed particular concern for reviving the rural economy and for lightening the tax burden of the peasants. Though generally humane in civil matters, he dealt harshly with those who threatened his reign from within China. His conduct of foreign affairs was a skillful combination of diplomacy and the use of force. His descendants continued the process of consolidating and expanding the empire.